Rescue teams were in the early stages of combing a region razed by a Category 4 hurricane that flattened blocks, collapsed buildings and left infrastructure crippled.

Some of the hardest-hit communities have yet to report any fatalities, and although officials said they hoped they would find survivors, a resigned gloom was setting in throughout the disaster zone.

Dr Jay Radtke, the medical examiner for some of the areas of most concern, including Panama City and Mexico Beach, said he could not release any information on the number of dead in the six Panhandle counties under his jurisdiction.

"We are swamped," he said. "It's a disaster zone down here."

At a news conference on Friday afternoon in Marianna, Florida, Sheriff Lou Roberts confirmed three storm-related deaths in Jackson County.

The authorities in Virginia said five people had died, including several who had drowned and a firefighter who was responding to an emergency call. Two other people were feared dead. Four deaths occurred in Gadsden County, west of Tallahassee, according to Lieutenant Anglie Hightower, a spokesman for the sheriff's office.

The victims included a man who died when a tree crashed down on his home in Greensboro.

An 11-year-old girl, Sarah Radney, was killed on Wednesday when a carport was torn away and sent hurtling into a modular home in Seminole County, Georgia.

North Carolina officials reported two more deaths on Friday, raising the death toll there to three. The authorities said a man and a woman had died in McDowell County when their car struck a large tree that had fallen on a road.

At least 1.5 million customers were without electricity in states stretching from Florida to Virginia. Many health institutions in Florida remained closed, including four hospitals, 13 nursing homes and 14 assisted living facilities, according to information distributed at a senior federal leadership briefing on Friday and shared with The New York Times.

The figures were slightly higher than those distributed by Florida's Agency for Health Care Administration. Several dialysis centers were also closed.

US President Donald Trump said on Friday that he would visit Florida and Georgia next week.

"People have no idea how hard Hurricane Michael has hit the great state of Georgia," he said on Twitter.

People have no idea how hard Hurricane Michael has hit the great state of Georgia. I will be visiting both Florida and Georgia early next week. We are working very hard on every area and every state that was hit - we are with you!

The Straits Times

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